Figure 1.

Group Psychophysical Results

Spatial resolution for pain (left panel) and touch (right panel) on the fingertip (green) and hand dorsum (black). Participants were required to discriminate the locations of two successive stimuli, aligned along the proximal-distal axis of the targeted body part. The x axis shows the spatial separation between the two stimuli (negative values indicate that the second stimulus was distal to the first stimulus). The y axis shows the proportion of trials in which the second stimulus was perceived as more proximal than the first. Individual data were fitted by cumulative Gaussian functions. Data in the figure show the average (+ SD) of ten participants. The steeper curves for the discriminations on the fingertip show that spatial resolution is higher on the fingertips than on the hand dorsum for both pain and touch. See also Movie S1.